The present invention is directed to the field of power driven wheelchairs, in general, and more particularly, to a method and apparatus for reprogramming a programmed controller of a power driven wheelchair.
Power driven wheelchairs which may be of the type manufactured by Invacare Corporation of Elyria, Ohio, for example, generally include right and left side drive wheels driven by a motor controller via respectively corresponding right and left side drive motors, all of which being disposed on the wheelchair. An exemplary illustration of such a motor drive arrangement is shown in the schematic of FIG. 1. Referring to FIG. 1, a motor drive controller 10 which may be an Invacare MK IV™ controller, for example, controls drive motors 12 and 14 which are mechanically linked respectively to the right side and left side drive wheels of the wheelchair. The controller 10 includes a microcontroller 15 which may be programmed with a plurality of drive programs, each suited for a particular operating environment of the wheelchair.
A user interface 16 which may include a joystick 18 and selection switches (not shown) operable by a user is also disposed on the wheelchair in a convenient location to the user. The user interface 16 is generally interfaced to the microcontroller 15 over a two wire serial coupling 20 to permit the user to select a drive program appropriate for operating the wheelchair in its environment and to adjust the direction and speed of the wheelchair within the selected drive program. In the present example, a main program of the microcontroller 15 which may contain the plurality of drive programs is stored in a non-volatile memory 19, like a read only memory (ROM), for example, which may be integrated into the microcontroller 15 or may be a separate component thereof.
The motor controller 10 is generally powered by a battery source 22, which may be 24 volts, for example, also disposed on the wheelchair. The drive motors 12 and 14 may be of the permanent magnet type and may be either a gearless, brushless AC motor or a brush type DC motor. The microcontroller 15 is interfaced and responsive to the user interface 16 to control drive signals 24 and 26 to motors 12 and 14, respectively, via a power switching arrangement configured in accordance with the motor type being driven. The power switching arrangement may be powered by the 24V battery 22. Thus, as the user adjusts the speed and direction of the wheelchair via the joystick of interface 16, appropriate drive signals 24 and 26 are controlled by motor controller 10 via microcontroller 15 to drive the motors 12 and 14 accordingly.
Motor controller 10 generally controls motor speed to the user setting utilizing a closed loop controller programmed in the microcontroller 15. Actual speed of each motor 12 and 14 may be derived from signals 28 and 30 respectively sensed therefrom. For example, for AC motors, a Hall Effect sensor may be disposed at the motor for sensing and generating a signal representative of angular position. The signals 28 and 30 are coupled to the microcontroller 15 which may be programmed to derive motor speed from a change in angular position for use as the actual speed feedback signal for the closed loop speed control of the motor. For DC motors, the voltage Va across the armature and armature current Ia may be sensed from each motor 12 and 14 and provided to the microcontroller 15 via lines 28 and 30, respectively. Microcontroller 15 may under programmed control derive the actual speed of each motor 12 and 14 from the respective voltage Va and current Ia measurements thereof for use as the speed feedback signal for the respective closed loop speed control of each motor 12 and 14.
In addition, interaction with the motor controller 10 is performed through a remote programmer 34 which may be electrically coupled to a port of the microcontroller 15 via signal lines 36, for example. Each remote programmer 34 may include a screen 38 for displaying interactive text and graphics and a plurality of pushbuttons 40 for communicating with the microcontroller 15 which is programmed to interact with the programmer 34. A dealer is generally provided with one or more remote programmers for rendering the wheelchair unique to the user's safe operating capabilities.
From time to time, the non-volatile ROM 19 may have to be reprogrammed and/or updated to more recent program versions which may be accomplished either in the field or at the factory or a service center. In some motor controllers, the programmed ROM 19 may be embodied in an integrated circuit or chip, either as part of the microcontroller 15 or separate therefrom. In these cases, the chip containing the programmed ROM 19 is removably disposed in a socket of a printed circuit (PC) card of the motor controller assembly 10. If the ROM 19 has to be reprogrammed or updated, the chip is removed from the socket and sent to the factory or authorized service center for processing. This renders the wheelchair out of service for an undesirable period of time.
Alternatively, some wheelchair dealerships are equipped with specialized converters and programming devices which permit reprogramming or updating of programs of the ROM 19 on the PC card. Generally, this process is not performed by a lay person, but rather performed by a skilled technician employed by the dealership. In these instances, the cost of the specialized equipment and skilled technician is borne by the dealership.
The dealers would prefer servicing the wheelchair themselves without having to send components back to the factory or service centers for reprogramming and/or updating of operational programs. However, the expense of the specialized equipment and employment of a skilled technician for performing this service is quite onerous to the dealer. Accordingly, it is desirable to simplify the process of reprogramming and/or updating the operational programs of the wheelchair at least to the point where it may be performed by a lay person. The present invention satisfies this desire.